Calcite is the principal mineral in limestone and marble, two very common rocks that make up a significant portion of the Earth’s crust.

Prized since antiquity for its warm, golden luster and similar appearance to gold, Pyrite has earned its spot in many collectors’ displays. The mineral gets its name from the Greek, meaning “of fire,” for its ability to create sparks when struck against steel. Top localities include Spain, Italy, Peru, and Washington State, all of which produce Pyrite crystals at collectable sizes with appealing aesthetics that set them apart from the majority of deposits around the world. There is a surprising amount of diversity between localities, allowing collectors to identify a specimen’s origin by appearance alone. Pyrite from Spain tends to be sharply cubic and exceptionally smooth -as if it has been carved and polished prior to discovery- while specimens from Peru, although sharing the cubic Spanish form, have a lovely, striated texture to them. Italian Pyrite displays complicated, modified octahedral shapes.

Often called “Fool's Gold” due to a case of mistaken identity, pyrite has a gold-to-brassy metallic hue and a tendency to crop up where gold is mined, but it is still quite the specimen to behold. The metallic luster of pyrite has led to some ancient Mesoamerican cultures to use larger specimens as mirrors